https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102379
Bug ID: 102379
Summary: missing -Wnarrowing even in instantiated template
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
Prompted by pr102378 (and looking for examples where G++ does issue diagnostics
for template code): G++ fails to diagnose the following invalid code, in both
the uninstantiated template and in the explicitly instantiated one.
$ cat t.C && gcc -O2 -S -Wall -std=c++11 -Wnarrowing t.C
template <class T>
int f ()
{
int i = { 2.2 }; // missing -Wnarrowing
return i;
}
template <class T>
int g ()
{
int i = { 2.2 }; // missing -Wnarrowing despite explicit instantiation
return i;
}
template <int> int g ();
Clang diagnoses both:
$ clang -S -Wall t.C
t.C:4:13: error: type 'double' cannot be narrowed to 'int' in initializer list
[-Wc++11-narrowing]
int i = { 2.2 }; // missing -Wnarrowing
^~~
t.C:4:13: note: insert an explicit cast to silence this issue
int i = { 2.2 }; // missing -Wnarrowing
^~~
static_cast<int>( )
t.C:4:13: warning: implicit conversion from 'double' to 'int' changes value
from
2.2 to 2 [-Wliteral-conversion]
int i = { 2.2 }; // missing -Wnarrowing
~ ^~~
t.C:11:13: error: type 'double' cannot be narrowed to 'int' in initializer list
[-Wc++11-narrowing]
int i = { 2.2 }; // missing -Wnarrowing despite explicit instantiation
^~~
t.C:11:13: note: insert an explicit cast to silence this issue
int i = { 2.2 }; // missing -Wnarrowing despite explicit instantiation
^~~
static_cast<int>( )
t.C:11:13: warning: implicit conversion from 'double' to 'int' changes value
from 2.2 to 2 [-Wliteral-conversion]
int i = { 2.2 }; // missing -Wnarrowing despite explicit instantiation
~ ^~~
2 warnings and 2 errors generated.
